The present invention generally relates to nondestructive evaluation of metallic structures and, more particularly, is concerned with a pulsed eddy current two-dimensional sensor array probe and system for electrically conducting component inspection.
The presence of surface cracks and subsurface flaws in metallic structures, such as aircraft skin structures, have the potential to lead to catastrophic failure. Various inspection methods have been used heretofore for crack and flaw detection with varying degrees of success.
One prior art inspection method uses eddy current probes which can give an indication of depth to ascertain crack and flaw severity. The probes requires close contact with the part and have limited resolution and inspection speed. Also, complicated contour following is needed to inspect curvatures of some parts. Lift off between the probes and the part is a major concern. Full coverage with eddy current probes is very time consuming, which leads to spot checking which may miss critical crack and defect areas.
Consequently, a need still exists for an innovation which will provides a solution to the aforementioned problem without introducing any new problems in place thereof.
The present invention provides a pulsed eddy current two-dimensional sensor array probe, system and data visualization for electrically conducting component inspection designed to satisfy the aforementioned need. The probe uses a two-dimensional array of magnetic field sensors for inspection of electrically conducting components without requiring mechanical scanning. A coil (solenoid) is used to transmit an electromagnetic pulse of a fixed duration into a component. The induced eddy current penetrates the structure and serves to produce a pattern of electromagnetic transient field above a defect. The two-dimensional array of sensors is located in a plane within the drive coil. Static scanning is employed to collect time evolution response of the magnetic field from all the sensors. This is performed by electronically switching the sensors while the probe is placed in a stationary position on the conducting structure. The response from the sensors is processed to determine the material thickness with a two-dimensional map representing a full field of view.
In one embodiment of the present invention, a pulsed eddy current two-dimensional sensor array probe for electrically conducting component inspection is provided which comprises a drive coil disposed adjacent to a structure under inspection, a pulse generator connected to the drive coil and operable to energize in a pulsed manner the drive coil to transmit transient electromagnetic flux into the structure under inspection, and an array of sensors arranged in a two-dimensional array and substantially surrounded by the drive coil and operable to sense and generate output signals from the transient electromagnetic flux in the structure under inspection.
In another embodiment of the present invention, a pulsed eddy current two-dimensional sensor array system for electrically conducting component inspection is provided which comprises a pulsed eddy current two-dimensional sensor array probe for transmitting in a pulsed manner a transient electromagnetic flux into a structure under test and for sensing and generating output signals from the transient electromagnetic flux in the structure under inspection, and a data acquisition apparatus for receiving and processing the output signals and outputting the processed signals in the form of a two-dimensional image made up of pixels that correspond to the array of sensors. The two-dimensional image is formed by a given gray level to the amplitude of an informative parameter that is computed for each individual sensor in the two-dimensional array. Each element (pixel) of the image is located according to the spatial position of the sensor in the array.